Scleractinia Boume, 1900

Arrigoni, Roberto, Stolarski, Jarosław, Terraneo, Tullia I., Hoeksema, Bert W., Berumen, Michael L., Payri, Claude, Montano, Simone & Benzoni, Francesca, 2023, Phylogenetics and taxonomy of the scleractinian coral family Euphylliidae, Contributions to Zoology 92 (2), pp. 130-171 : 146-150

Order Scleractinia Boume, 1900

Family Euphylliidae Milne Edwards & Haime, 1857

Synonyms: Galaxeinae Vaughan & Wells, 1943; Euphylliinae Alloiteau, 1952 ; Euphyllidae Veron, 2000 ; Euphylliidae Veron, 2002 .

Type genus: Euphyllia Dana, 1846 .

Diagnosis: Colonial. Budding extracalicular and, typically, intracalicular. Corallites monomorphic; discrete or uni- or multi serial. Coenosteum bay be fused walls, extensive (Ẑ corallite diameter), or phaceloid. Coenosteum vesicular if present. Calice of width variable (<4 mm, 4–15 mm, or> 15 mm) and relief medium to high (Ẑ 3 mm). Costosepta mostly not confluent if present. Number of septa variable (<3 cycles, 3 cycles, or Ẑ 3 cycles).Free septa regular.Septal spacing variable (<6 septa, 6–11 septa, or> 11 septa per 5 mm). Costosepta may be equal or unequal in relative thickness. If present, columellae may be lamellar, trabecular compact (1–3 threads), Downloaded from Brill.com 08/29/2023 05:29:52PM via free access or reduced to inner septa margin processes, of sizes variable relative to calice width (<1/4 or Ẑ 1/4), with linkage absent or continuous. Paliform lobes absent. Endotheca abundant (vesicular). Microtexture of septal faces variable (delicately granular, delicately grainy with low but pointed granulae arranged in rows parallel to septal margin, shingles absent or small-sized or arranged into unique, meandering “persian lamb fur” pattern). Bundles of td fibers variable (not well delineated perpendicular to septal surface, well delineated perpendicular/slightly oblique to septal surface, in some axial septa regions arranged into elongated bundles as consequence of continuous growth of shingles). rads closely spaced, sometimes zig-zag mid-septal or not well delineated. Polyp tentacles retracted, partially/fully extended, or fully extended at daytime, of shape simple or complex.

Genera included: Euphyllia Dana, 1846 ; Coeloseris Vaughan, 1918 ; Ctenella Matthai, 1928 ; Fimbriaphyllia Veron & Pichon, 1980 ; Galaxea Oken, 1815 ; Gyrosmilia Milne Edwards & Haime, 1851 ; (?) Montigyra Matthai, 1928 ; (?) Simplastrea Umbgrove, 1939 .

Taxonomic remarks: Euphylliidae was firstly established by Milne Edwards & Haime (1857) as Euphylliaceae at the lower-level rank of “ agèle ”. Therefore, subsequent descriptions, including Euphylliinae Alloiteau, 1952 , Euphyllidae Veron, 2000 , and Euphylliidae Veron, 2002 , are either junior synonym or misspelling (see iczn, 2011). Galaxeinae Vaughan & Wells, 1943 was originally established as a sub-family of Oculinidae by Vaughan & Wells (1943) but, since its type genus Galaxea is nested within to Euphylliidae , Galaxeinae is herein considered a junior synonym of Euphylliidae . Following the molecular results of Fukami et al. (2008), Euphylliidae was formally re-organised at the genus level by Budd et al. (2012) to include only members of clade V sensu Fukami et al. (2008), namely Euphyllia , Galaxea , and Ctenella . The authors also transferred to Euphylliidae three genera that were not genetically analysed but considered to be morphologically similar to euphylliids, namely Gyrosmilia , Montigyra , and Simplastrea . Subsequently, Luzon et al. (2017, 2018) resurrected Fimbriaphyllia as a valid genus of Euphylliidae , restoring the monophyly of Euphyllia . In our study, we showed that Gyrosmilia clustered within Euphylliidae . Additionally, we found Coeloseris included within Euphylliidae based on both molecular and morphological data, confirming previous evidence by Kitahara et al. (2012b) and Arrigoni et al. (2017). As such, Coeloseris is herein transferred to Euphylliidae .

Morphological remarks: All investigated genera of Euphylliidae are characterised by extracalicular budding, absent polymorphism, regular free septa, absent paliform lobes, and abundant endotheca. The states of the remaining 13 macromorphological characters are variable among genera. It is noteworthy to highlight that Pachyseris speciosa , belonging to the genus that represents the sister taxon of Euphylliidae in the molecular phylogenetic tree of Scleractinia (see Kitahara et al., 2016), possesses absent or poorly developed free septa and sparse endotheca. The two species of Agariciidae studied here, namely Gardineroseris planulata and Pavona cactus , show sparse endotheca, slightly unequal costosepta in relative thickness, and discontinuous columella linkages that are not found in the investigated euphylliids. From a micromorphological/microstructural perspective, the most distinct euphylliid subclade is represented by Galaxea species, which consistently form well developed shingles (or scale-like structures) arranged into unique, meandering “persian lamb fur” pattern on skeletal structures (septal faces, internal part of the wall; see also Stolarski, 2003). Noteworthy, less distinct shingles occur also in some species of Euphyllia , e.g., E. glabrescens , and in some examined specimens of the euphylliid sister taxon Pachyseris ( P. speciosa ). This character was found also in herein examined agariciids, i.e., G. planulata and P. cactus , and previously noted also in juvenile stages of other agariciids, i.e., Dactylotrochus and Leptoseris ( Kitahara et al., 2012b) . Shingles of unique morphology are particularly strongly developed in acroporids ( Stolarski et al., 2016).The occurrence of shingles may point to a common theme in the histological organisation of calicoblastic tissues in euphylliids and the mentioned euphylliid sister/outgroups, but with distinct and strong expression in some groups ( Galaxea -group or acroporids). The investigated euphylliid taxa show a tendency to develop granulae in rows parallel to the septal margins (clearly visible in Fimbriaphyllia ). This character is particularly well developed in agariciids where occasionally the rows of granulae may merge to form lists or meninae on septal faces as in Leptoseris (e.g., L. fragilis ) and Dactylotrochus ( Kitahara et al. 2012b) . The occurrence of granulae or merged granulae (menianae in some agariiciids), developed as structures parallel to septal margins, may point to a common biomineralization pattern, i.e., synchronous formation of rows of rads on lateral septal faces in the agariciid-euphylliid evolutionary lineage (noted also by Cuif et al., 2003). All euphylliids investigated here, and Pachyseris , but also agariciids and acroporids, develop closely spaced, often not well delineated rads on the septal margin.

Distribution: Euphylliidae is widely distributed on tropical and sub-tropical photic and mesophotic reefs of the Indo-Pacific, and absent in the eastern Pacific ( Veron, 2000; Loya et al., 2019).